boiler not cycling

[md1025]

I am having a problem with the boiler in my rented home,the problem is that the boiler runs non stop and only when i turn the rads off upstairs does it start to cycle and only 4 or 5 of the rads down stairs are warm to the touch,the boiler will cycle on for 2min 20 secs give or take and stays off 3mins 45secs give or take,the house has 7 bedrooms 2 bath rooms,2 of the bedrooms and a bathroom are upstairs in an attic conversion.The boiler is a heatage 60/90 and burner is an ecoflam minor 1, I think there both about 12 years old. The landlord has had 2 plumbers and a boilerman who serviced it in september and they keep telling me because the house is so big the boiler will keep running,none of them have done a fga of the boiler but are able to tell me the boiler is working fine,the boiler has used around 700l in the last 4 to 5 weeks

 

[dcawkwell]

How many radiators?
If you have 7 bedrooms I estimate you have about 20 radiators in the house.
So assuming 1.5kw per radiator so approx 35kW required.
If your boiler is less than this is it run all the time as the heat loss
is greater than the boiler can supply until the house reaches temperature.
If you have no wall thermostat there will be nothing to cut the boiler
off and the boiler will keep pumping heat into the house.
The boiler will only shut down when it's thermostat is satisfied. As you have found shutting the radiators down reduces the heat loss and the boiler can cycle. But even then the heat loss is great and it is only off for 3 minutes before the thermostat in the boiler is firing the boiler again.
No need for a flue gas analyser on this the boiler is running fine.
My house is 4 bedrooms and if I were to heat it properly I would easily expect to cost £150 a month on lpg to heat. So a house double this size your costs are in line.

Reduce costs by only heating the rooms you are using.

 

[md1025]

There is 18 rads 12 downstairs and 6 upstairs,why is the boiler cycling on n off so quickly, house has no room stats just on boiler no zone valves either and hot water cylinder has no stat,

 

[dcawkwell]

There is 18 rads 12 downstairs and 6 upstairs,why is the boiler cycling on n off so quickly, house has no room stats just on boiler no zone valves either and hot water cylinder has no stat,

Turn boiler down to it's lowest setting.

You need to get a room thermostat installed to cut the boiler off
when the main room gets to temperature. Otherwise the boiler
will keep on going keep the heat in the boiler at the temperature setting.

Boiler thermostat may be defective and not allowing enough
time between cycles. With all but one or two large radiators on.
The boiler should cycle may every 10 minutes or so. If not I would
perhaps swap the boiler thermostat as it is probably one of
the thermostat phial types that work by gas expansion. If the phial
is low on gas there won't be much time between off/on's of the boiler.

 

[dcawkwell]

There is 18 rads 12 downstairs and 6 upstairs,why is the boiler cycling on n off so quickly, house has no room stats just on boiler no zone valves either and hot water cylinder has no stat,

No room stat and no cylinder stat.
Heating is going to cost a packet. How does the boiler know when to stop??